Bipolar signal generating apparatus

Abstract

A bipolar signal generating apparatus for generating a bipolar signal having positive and negative polarities and comprising a switch means for connecting two terminals of a primary winding of a transformer with each other when the bipolar signal has a level of its neutral region.

What is claimed is: 
     
       1. In an apparatus for generating a bipolar signal from two kinds of signals which are related such that at a period of time at which one of said two signals has an "H" level the other signal has an "L" level, said bipolar signal having a positive level at a period of time at which said first signal has said "H" level having a negative level at a period of time at which said second signal has said "H" level and having a level of its neutral region at a period of time at which both said first and second signals have said "L" levels, respectively, the improvement comprising a transformer having a primary winding and a secondary winding, a first switch means for supplying a current to said primary winding flowing therethrough in one direction when said first signal has said "H" level, a second switch means for supplying a current to said primary winding flowing therethrough in a direction opposite to said direction and a third switch means for connecting two terminals of said primary winding with each other when both said first and second signals have said "L" levels, respectively. 
     
     
       2. The apparatus according to claim 1 wherein said third switch means is an analog switch. 
     
     
       3. The apparatus according to claim 1 wherein said first switch means is composed of a first transistor for connecting a direct current source to a first terminal of said primary winding when said first signal has said "H" level and a second transistor for connecting a second terminal of said primary winding to ground when said first signal has said "H" level, and said second switch means is composed of a third transistor for connecting said direct current source to said second terminal of said primary winding when said second signal has said "H" level and a fourth transistor for connecting said first terminal of said primary winding to ground when said second signal has said "H" level. 
     
     
       4. The apparatus according to claim 1 wherein said primary winding of said transformer is provided with an intermediate tap and said third switch means is connected between said two terminals of said primary winding and ground.